feat(psci): add support for OS-initiated mode

This patch adds a `psci_validate_state_coordination` function that is
called by `psci_cpu_suspend_start` in OS-initiated mode.

This function validates the request per sections 4.2.3.2, 5.4.5, and 6.3
of the PSCI spec (DEN0022D.b):
- The requested power states are consistent with the system's state
- The calling core is the last running core at the requested power level

This function differs from `psci_do_state_coordination` in that:
- The `psci_req_local_pwr_states` map is not modified if the request
  were to be denied
- The `state_info` argument is never modified since it contains the
  power states requested by the calling OS

This is conditionally compiled into the build depending on the value of
the `PSCI_OS_INIT_MODE` build option.

Change-Id: I667041c842d2856e9d128c98db4d5ae4e4552df3
Signed-off-by: Wing Li <wingers@google.com>

1 files changed, 36 insertions, 10 deletions

diff --git a/lib/psci/psci_main.c b/lib/psci/psci_main.c
index 4b5fc81d7..fe12f06ba 100644
--- a/lib/psci/psci_main.c
+++ b/lib/psci/psci_main.c
@@ -60,6 +60,10 @@ int psci_cpu_suspend(unsigned int power_state,
 	entry_point_info_t ep;
 	psci_power_state_t state_info = { {PSCI_LOCAL_STATE_RUN} };
 	plat_local_state_t cpu_pd_state;
+#if PSCI_OS_INIT_MODE
+	unsigned int cpu_idx = plat_my_core_pos();
+	plat_local_state_t prev[PLAT_MAX_PWR_LVL];
+#endif
 
 	/* Validate the power_state parameter */
 	rc = psci_validate_power_state(power_state, &state_info);
@@ -95,6 +99,18 @@ int psci_cpu_suspend(unsigned int power_state,
 		cpu_pd_state = state_info.pwr_domain_state[PSCI_CPU_PWR_LVL];
 		psci_set_cpu_local_state(cpu_pd_state);
 
+#if PSCI_OS_INIT_MODE
+		/*
+		 * If in OS-initiated mode, save a copy of the previous
+		 * requested local power states and update the new requested
+		 * local power states for this CPU.
+		 */
+		if (psci_suspend_mode == OS_INIT) {
+			psci_update_req_local_pwr_states(target_pwrlvl, cpu_idx,
+							 &state_info, prev);
+		}
+#endif
+
 #if ENABLE_PSCI_STAT
 		plat_psci_stat_accounting_start(&state_info);
 #endif
@@ -110,6 +126,16 @@ int psci_cpu_suspend(unsigned int power_state,
 		/* Upon exit from standby, set the state back to RUN. */
 		psci_set_cpu_local_state(PSCI_LOCAL_STATE_RUN);
 
+#if PSCI_OS_INIT_MODE
+		/*
+		 * If in OS-initiated mode, restore the previous requested
+		 * local power states for this CPU.
+		 */
+		if (psci_suspend_mode == OS_INIT) {
+			psci_restore_req_local_pwr_states(cpu_idx, prev);
+		}
+#endif
+
 #if ENABLE_RUNTIME_INSTRUMENTATION
 		PMF_CAPTURE_TIMESTAMP(rt_instr_svc,
 		    RT_INSTR_EXIT_HW_LOW_PWR,
@@ -142,12 +168,12 @@ int psci_cpu_suspend(unsigned int power_state,
 	 * might return if the power down was abandoned for any reason, e.g.
 	 * arrival of an interrupt
 	 */
-	psci_cpu_suspend_start(&ep,
-			    target_pwrlvl,
-			    &state_info,
-			    is_power_down_state);
+	rc = psci_cpu_suspend_start(&ep,
+				    target_pwrlvl,
+				    &state_info,
+				    is_power_down_state);
 
-	return PSCI_E_SUCCESS;
+	return rc;
 }
 
 
@@ -187,12 +213,12 @@ int psci_system_suspend(uintptr_t entrypoint, u_register_t context_id)
 	 * might return if the power down was abandoned for any reason, e.g.
 	 * arrival of an interrupt
 	 */
-	psci_cpu_suspend_start(&ep,
-			    PLAT_MAX_PWR_LVL,
-			    &state_info,
-			    PSTATE_TYPE_POWERDOWN);
+	rc = psci_cpu_suspend_start(&ep,
+				    PLAT_MAX_PWR_LVL,
+				    &state_info,
+				    PSTATE_TYPE_POWERDOWN);
 
-	return PSCI_E_SUCCESS;
+	return rc;
 }
 
 int psci_cpu_off(void)